1. Field of the Invention
The present invention relates to disposable absorbent articles, and more particularly to disposable absorbent articles having graphics thereon. The invention also relates to processes and apparatus for making absorbent articles having graphics thereon whereby the graphics are made using ultrasonic thermal imaging methods.
2. Description of Related Art
Absorbent articles, and in particular disposable absorbent articles such as infant diapers or training pants, adult incontinence products and other such products, typically are constructed with a moisture-impervious outer backing sheet (or xe2x80x9cbacksheetxe2x80x9d), a moisture-pervious body-contacting inner liner sheet (or xe2x80x9ctopsheetxe2x80x9d), and a moisture-absorbent core (or xe2x80x9cabsorbent corexe2x80x9d) sandwiched between the liner sheet and the backing sheets. These disposable absorbent articles oftentimes include additional features such as elastic waist bands, elastic leg bands, and stretchable side panels. Further, decorative graphics can be incorporated into the disposable absorbent article for aesthetic and functional purposes.
Disposable absorbent articles generally are assembled on an automated production line by separately supplying the individual components of the absorbent article to the production line at predetermined locations along the machine direction, and layering the individual components to form an integrated absorbent article. Various methods are available for bringing these individual components together so that the components in the integrated product are in a desired relation with respect to each other. In bringing these individual components together, various known methods have been used to sense the position of a particular component, and then to adjust the placement of subsequent components in order to properly position them with respect to the previously sensed component. Proper placement of the components is even more important when one or more component(s) have graphics or other identifying marks printed or embossed thereon.
U.S. Pat. Nos. 5,286,543 and 5,235,515 to Ungpiyakul et al. disclose a system for selectively providing predetermined segments of web material that have printed graphics to an absorbent article production line using a reference marker that is incorporated into the final assembled absorbent article. Generally stated, the method includes supplying the web material at a web speed and sensing a reference mark on the web material to generate at least one reference mark datum which is associated with a selected web segment. The ""543 Patent discloses that the predetermined segments of web material comprise discrete graphic patches corresponding to the tape landing zone of the diaper. The patch is said to have a predetermined set of graphics which are xe2x80x9ccongruously entire.xe2x80x9d The patches are also said to abruptly change from graphics set to graphics set and, therefore, from diaper to diaper because there is no modulating transition between the adjacent compositions formed on the original supply roll of web material. The patches are said to be provided with reference markers delineating the boundaries between individual web or patch segments. The reference markers comprise any signaling mechanism which is recognizable by a machine.
U.S. Pat. No. 5,766,389 to Brandon et al. discloses a process for controllably registering a plurality of components of a continuously moving first layer with a plurality of reference marks on a continuously moving second layer with pre-printed graphics. Brandon is said to controllably register a graphic within a designated area of the absorbent article. The ""543 patent and Brandon both require transfer of a graphic from one supply of web material to the absorbent garment by cutting and placing the supply of web material including the graphic(s) on the absorbent garment.
Embossed plastic films are known in the art and are used as a substitute for textiles. Embossed films may be used for many different purposes such as diaper liners, panty liners and sanitary napkins. Examples of embossed films are disclosed in U.S. Pat. Nos. 3,911,187, 4,518,643, and 5,229,186, the disclosures of each of which are incorporated by reference herein in their entirety, and in a manner consistent with this disclosure. Embossing typically is used to alter the xe2x80x9cfeelxe2x80x9d or xe2x80x9chandxe2x80x9d of the fabric, and to add a decorative design. Different methods for embossing non-woven fabrics and films are known, some of which are designed primarily to alter the strength properties of the fabric, as disclosed in U.S. Pat. No. 4,592,943, the disclosure of which is incorporated by reference herein in its entirety. The ""943 patent discloses heating a non-woven web as it passes between two grids so that the grids impart a pattern of rectangular densified areas to the web. Another method referred to as pattern roll embossing is disclosed in U.S. Pat. No. 4,774,124, the disclosure of which is incorporated by reference herein in its entirety, which discloses using a pair of pattern rollers to emboss non-woven fabric. Patterned and embossed non-woven materials also are described in U.S. Pat. No. 5,599,420, the disclosure of which is incorporated by reference herein in its entirety, and in a manner consistent with this disclosure. The ""420 patent discloses a non-woven fabric comprising continuous polymeric filaments extending continuously along the length of the fabric that are bonded together with a heat-activated adhesive. Upon embossing, the fabric is said to have a pattern of densified areas separated by high loft areas.
Thermoplastic films have been bonded to one another with ultrasonic energy using embossed patterns or pins. Ultrasonic bonding and embossing techniques are disclosed in, for example, U.S. Pat. No. 3,562,041 (ultrasonic joining of materials according to a pattern), U.S. Pat. No. 3,733,238 (vibration welding of sheet materials), U.S. Pat. No. 4,668,316 (welding thin thermoplastic film by ultrasonic energy), U.S. Pat. No. 5,096,532 (ultrasonic rotary horn), U.S. Pat. No. 5,110,403 (high efficiency ultrasonic rotary horn), U.S. Pat. No. 5,846,377 (welding thermoplastic work pieces using ultrasonic energy), U.S. Pat. No. 6,036,796 (ultrasonic welding apparatus and method), U.S. Pat. No. 6,165,298 (patterned anvil roll to effect bonding, cutting, embossing, perforating), and U.S. Pat. No. 6,277,224 (ultrasonic perforator), the disclosures of each of which are incorporated by reference herein in their entirety. It also is known to use heated rolls to thermally emboss a web of material, as disclosed, for example, in U.S. Pat. Nos. 5,229,186 and 6,041,701, the disclosures of each of which are incorporated by reference herein in their entirety.
It also is common to use inks, e.g., adhesive inks, to form an image on a non-woven fabric. U.S. Pat. No. 5,503,076, the disclosures of which is incorporated by reference herein in its entirety, and in a manner consistent with this disclosure, discloses laminating a non-woven web facing layer and a substrate layer with colored adhesive inks that are applied in a discrete bond pattern. Thermal imaging techniques useful in forming images on various substrates are disclosed in, for example, U.S. Pat. Nos. 5,716,477 and 6,117,562, the disclosures of each of which are incorporated by reference herein in their entirety, and in a manner consistent with this disclosure.
It would be desirable to provide an absorbent garment having a graphic formed thereon, whereby the image can be formed on the backsheet or outer liner in-line during manufacture of the article. It also would be desirable to provide a method of forming a viewable image on an absorbent article that is cost efficient and easy to carry out. It would further be desirable to provide a method of forming an image on a moving web of material that is efficient, can operate at high line speeds, does not damage the moving web when the system shuts down, and that enables a more precise application of heat.
Accordingly, it is a feature of an embodiment of the invention to provide an absorbent garment and a method of making the absorbent garment whereby a viewable image is formed directly on the garment as it is manufactured in a cost-efficient manner. It is another feature of an embodiment of the invention to provide an efficient method of forming an image on a moving web at high speeds without causing significant damage and/or deformation of the moving web. It also is a feature of an embodiment of the invention to form an image on a moving web in a cost-efficient manner without causing significant damage and/or deformation to the moving web, and then transfer the image to a component in an absorbent garment.
In accordance with these and other features of various embodiments of the invention, there is provided a method of making an absorbent article, wherein each absorbent article comprises an image either formed on a moving web that forms a part of the article, or on an applique layer that then is subsequently adhered to or otherwise associated with the absorbent article. The method includes imparting sufficient ultrasonic energy with an ultrasonic assembly to the moving web or applique layer to raise the surface temperature of the moving web only in the areas where the image is to be formed to slightly above the melting temperature of the moving web or applique layer, and thereby form the image. In accordance with the method, the ultrasonic horn vibrates transversely to the direction of the moving web or applique layer, and preferably only briefly comes into contact with the material that is imaged when the horn is fully extended (e.g., at its greatest amplitude of vibration). It is particularly preferred in the invention that the amount of energy imparted by the ultrasonic horn be controlled to prevent forming a hole in the web or applique layer that can be caused by melting all the way through the material.
The method according to another embodiment of the invention is a method of forming an absorbent article that includes providing an absorbent core, and a top sheet material. The method also includes forming an image on a moving liquid impermeable back sheet material by imparting sufficient ultrasonic energy with an ultrasonic assembly to the back sheet material to raise the surface temperature thereof only in the areas where the image is to be formed to slightly above the melting temperature of the back sheet layer to thereby form a liquid impermeable imaged back sheet material. The method includes providing a liquid impermeable imaged back sheet material, and forming an absorbent article at a forming station by disposing the absorbent core between the top sheet material and the liquid impermeable imaged back sheet material.
In accordance with another feature of an embodiment of the invention, there is provided a method of making an absorbent article comprising supplying an absorbent core, a top sheet material and a liquid impermeable back sheet material. The method also includes forming an image on a moving applique layer by imparting sufficient ultrasonic energy with an ultrasonic assembly to the applique layer to raise the surface temperature thereof only in the areas where the image is to be formed to slightly above the melting temperature of the applique layer to form an imaged applique layer. The method further includes forming a continuously moving absorbent core assembly at a forming station by disposing the absorbent core between the top sheet material and the liquid impermeable back sheet material. In accordance with this embodiment, the method also includes providing a continuously moving imaged applique layer, and disposing the continuously moving imaged applique layer on a surface of the continuously moving absorbent core assembly.
In accordance with another feature of an embodiment of the invention, there is provide a method of imparting an image to an absorbent article that includes providing an absorbent core, a top sheet material, and a liquid impermeable back sheet material. The method further includes forming a continuously moving absorbent core assembly having at least one outer layer at a forming station by disposing the absorbent core between the top sheet material and the liquid impermeable back sheet material. The method also includes forming an image on the continuously moving absorbent core assembly by imparting sufficient ultrasonic energy with an ultrasonic assembly to the at least one outer layer to raise the surface temperature thereof only in the areas where the image is to be formed to slightly above the melting temperature of the outer layer.
In accordance with yet another embodiment of the invention, there is provided an apparatus for imparting an image to a moving non-woven web, the apparatus including a mechanism for transporting the web in a machine direction and past an ultrasonic assembly, an imaging roll capable of deforming the surface of the web without punching holes there through, whereby the deformed surface corresponds to either a positive or a negative of the image to be formed. The apparatus further includes an ultrasonic assembly positioned relative to the moving web such that the minimum distance between the ultrasonic horn at rest (e.g., prior to excitation) and the deformed surface of the web is from about 0.0005 to about 0.005 inch. The apparatus further includes a mechanism for controlling the amount of energy imparted to the ultrasonic assembly such that the ultrasonic assembly provides sufficient ultrasonic energy to the moving web to raise the surface temperature of the deformed surfaces to slightly above the melting temperature of the web only in the areas where the image is to be formed.
In yet another embodiment of the present invention, there is provided an apparatus for forming an absorbent garment having an image thereon, the apparatus including a mechanism for supplying top sheet material, a mechanism for supplying back sheet material, and a mechanism for supplying an absorbent core. The apparatus also includes a forming station for bringing the back sheet material, top sheet material and absorbent core into engagement with one another by disposing the absorbent core between the top sheet material and the back sheet material.
The apparatus also includes a mechanism for transporting a web past an ultrasonic assembly, an imaging roll capable of deforming the surface of the web without punching holes there through, whereby the deformed surface corresponds to either a positive or a negative of the image to be formed. The apparatus further includes an ultrasonic assembly positioned relative to the moving web such that the minimum distance between the ultrasonic horn at rest (e.g., prior to excitation) and the deformed surface of the web is from about 0.0005 to about 0.005 inch. The apparatus further includes a mechanism for controlling the amount of energy imparted to the ultrasonic assembly such that the ultrasonic assembly provides sufficient ultrasonic energy to the moving web to raise the surface temperature of the deformed surfaces to slightly above the melting temperature of the web only in the areas where the image is to be formed.
In one embodiment, the moving web is the back sheet material, and the ultrasonic assembly is disposed in the machine direction either prior to, or after the forming station. In another embodiment, the web is an applique layer, the ultrasonic assembly is disposed in a position independent from the forming station, and the apparatus further includes a mechanism for cutting and disposing the applique layer containing the image on the back sheet material either prior to, or after the back sheet material travels through the forming station.